Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C57/00—Unsaturated compounds having carboxyl groups bound to acyclic carbon atoms
  • C07C57/02—Unsaturated compounds having carboxyl groups bound to acyclic carbon atoms with only carbon-to-carbon double bonds as unsaturation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
  • C07C69/62—Halogen-containing esters
  • C07C69/65—Halogen-containing esters of unsaturated acids
  • C07C69/653—Acrylic acid esters; Methacrylic acid esters; Haloacrylic acid esters; Halomethacrylic acid esters

Definitions

• the present invention relates to a process for the preparation of bromo-substituted aromatic esters of ⁇ , ⁇ -unsaturated acids. More particularly the invention relates to a process for the preparation of esters of the formula: ##STR2## wherein: n is 1 or 2,
• R and R' are hydrogen or alkyl.
• Acrylates encompassed by formula I, in which R' is hydrogen, are useful intermediates for the preparation of polymeric flame retardant agents (e.g., U.S. Pat. No. 4,128,709), but they may be useful as monomeric flame-retardant agents for certain applications, as described, e.g., in the copending Israeli Patent Application No. 86604 of the same applicant.
• the monomers obtained according to the process of the invention also form part of the present invention.
• the monomer pentabromobenzyl monoacrylate which has been shown by the applicant to possess outstanding flame-retardant properties.
• Providing this monomer in high yield is advantageous also when it is desired to use it as an intermediate for the preparation of the well-known flame retardant material polypentabromobenzyl acrylate, as will be apparent to the skilled chemist.
• the process according to the invention comprises reacting a salt of an ⁇ , ⁇ -unsaturated acid and an alkali with a bromo-substituted benzyl halide in an inert, water-immiscible solvent and in the presence of a phase-transfer catalyst.
• the inert solvent is a substantially water-immiscible hydrocarbon and/or halocarbon, such as chlorobenzene, toluene, methylene chloride, chlorobromomethane, dibromomethane, mixtures of methylene chloride, chlorobromomethane and dibromomethane, ethylene dichloride and ethylene dibromide, and the alkali is a metal hydroxide, preferably NaOH, KOH or carbonates thereof.
• halocarbon such as chlorobenzene, toluene, methylene chloride, chlorobromomethane, dibromomethane, mixtures of methylene chloride, chlorobromomethane and dibromomethane, ethylene dichloride and ethylene dibromide
• the alkali is a metal hydroxide, preferably NaOH, KOH or carbonates thereof.
• the phase-transfer catalyst can be a conventional phase-transfer catalyst, such as a quaternary ammonium salt, for example Aliquat 336 (tricaprylylmethyl ammonium chloride), hexadecyltrimethyl ammonium chloride or tetrabutyl ammonium bromide.
• a quaternary ammonium salt for example Aliquat 336 (tricaprylylmethyl ammonium chloride), hexadecyltrimethyl ammonium chloride or tetrabutyl ammonium bromide.
• the molar ratio of the acid to PBB-Br may be between 1:1 and 1.8:1, preferably between 1.05:1 and 1.2:1.
• concentrations of reagents are such as to produce, at full conversion, a product concentration of 25-55%, preferably between 30% and 40%.
• the salts, such as NaBr and KBr formed in the reaction can be removed by hot filtration, and the product can then be precipitated by cooling the reaction mixture and recovered.
• the process of the invention presents a further important advantage, viz., that the mother liquor can be recycled and used for subsequent batches.
• the mother liquor can be recycled and used for subsequent batches.
• the product is thus obtained in a high purity and is useful as such in fire retardant applications. If higher purities are required, as in some copolymerization applications, the product may be further purified by recrystallization.
• a 500 ml three-necked flask provided with a mechanical stirrer, a thermometer and a condenser is filled with 292 ml solvent. 8.33 g NaOH is added. Next 15.0 g acrylic acid is added in portions. During the neutralisation ( ⁇ 30 min) the temperature is kept ⁇ 30° C.
• the mixture was filtered at the reaction temperature, and the filtrate was subjected to careful cooling to 0°-5° C., at which temperature the PBB-MA crystallizes out and can be easily filtered.
• the material was of high purity and did not require any further washing.
• the product had the same properties as in Example 1, and the yield was more than 90%.
• Example 1 was repeated, using equivalent amounts of tetrabutylammonium bromide instead of Aliquat 336. Comparable results were obtained.
• the reaction mixture contained 890 ml chlorobromomethane (CBM), 47.88 g (0.84 mol) KOH, 63.5 g (0.88 mol) of Acrylic acid, 396.2 g (0.7 mol) of PBB-Br and 8.0 g of Aliquat 336 in 30 ml solution.
• Example 11 was repeated, using the following solvents instead of CBM: MC, CBM, a 1:1:1 mixture of MC, CBM and DBM, EDC, EDB. In all cases comparable results were obtained.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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Cited By (9)

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Citations (2)

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• 1989
  • 1989-03-29 IL IL89791A patent/IL89791A0/xx unknown
• 1990
  • 1990-03-26 AT AT90105729T patent/ATE100433T1/de not_active IP Right Cessation
  • 1990-03-26 DE DE90105729T patent/DE69006065T2/de not_active Expired - Lifetime
  • 1990-03-26 EP EP90105729A patent/EP0390042B1/de not_active Expired - Lifetime
  • 1990-03-27 KR KR1019900004127A patent/KR0171892B1/ko not_active IP Right Cessation
  • 1990-03-28 US US07/500,679 patent/US5072028A/en not_active Expired - Lifetime
  • 1990-03-29 JP JP2079040A patent/JP2912972B2/ja not_active Expired - Lifetime

Patent Citations (2)

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